A process-based fire regime model (SPITFIRE) has been developed, coupled with
ecosystem dynamics in the LPJ Dynamic Global Vegetation Model, and used to explore
spatial and temporal patterns of fire regimes and the current impact of fire on the ter-
5 restrial carbon cycle and associated emissions of trace atmospheric constituents. The
model estimates an average release of 2.24 PgCyr-1 as CO2 from biomass burning
during the 1980s and 1990s. Comparison with observed active fire counts shows that
the model reproduces where fire occurs and can mimic broad geographic patterns in
the peak fire season, although the predicted peak is 1¿2 months late in some regions.
10 Modelled fire season length is generally overestimated by about one month, but shows
a realistic pattern of differences among biomes. Comparisons with remotely sensed
burnt-area products indicate that the model reproduces broad geographic patterns of
annual fractional burnt area over most regions, including the boreal forest, although interannual
variability in the boreal zone is underestimated. Overall SPITFIRE produces
15 realistic simulations of spatial and temporal patterns of fire under modern conditions
and of the current impact of fire on the terrestrial carbon cycle and associated emissions
of trace greenhouse gases and aerosols.